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Hydrochoric Seed Dispersal of Riparian Plants Follows Hydrological Patterns Closer Than Geomorphic Variation
Full text linkWater is an important dispersal vector for seeds of riparian plants, but little is known on how this form of dispersal, called hydrochory, varies throughout seasons and through geomorphically different areas. Therefore, we trapped seeds in 25 x 25 Astroturf mats along a free-flowing boreal river for an entire year. Sites mirrored the full range of geomorphic variation in the area and traps were emptied before and after the annual peak flow. The traps collected 2,062 seeds before the spring flood and 16,157 during the spring flood. While most of the seeds were deposited in the summer-low water traps (from now on "water edge") before the spring flood, they were distributed more equally in the riparian traps (defined as the level 40 cm above the water edge; from now on "riparian zone") during the spring flood. We found 77 species in total, of which 71 were at least recorded during the spring flood. Species numbers were higher at the water edge than at the riparian zone before and during the spring flood. Only 6.6% of the seeds, from 26 species, were viable. Most viable seeds were found in the water edge traps and, during the spring flood, in the riparian zone traps. While species that are primarily dispersed by water were not the most abundant among the viable seeds, they were the most species-rich group. This means that hydrochory is an important dispersal mechanism for riparian vegetation and an important contributor to riparian plant diversity in free-flowing rivers, and that changes in flow regimes, such as by flow regulation, can affect riparian vegetation composition
A global dataset of nitrogen fixation rates across inland and coastal waters
Full text linkBiological nitrogen fixation is the conversion of dinitrogen (N2) gas into bioavailable nitrogen by microorganisms with consequences for primary production, ecosystem function, and global climate. Here we present a compiled dataset of 4793 nitrogen fixation (N2-fixation) rates measured in the water column and benthos of inland and coastal systems via the acetylene reduction assay, 15N2 labeling, or N2/Ar technique. While the data are distributed across seven continents, most observations (88%) are from the northern hemisphere. 15N2 labeling accounted for 67% of water column measurements, while the acetylene reduction assay accounted for 81% of benthic N2-fixation observations. Dataset median area-, volume-, and mass-normalized N2-fixation rates are 7.1 mu mol N2-N m-2 h-1, 2.3 x 10-4 mu mol N2-N L-1 h-1, and 4.8 x 10-4 mu mol N2-N g-1 h-1, respectively. This dataset will facilitate future efforts to study and scale N2-fixation contributions across inland and coastal aquatic environments
ATG8ylation of vacuolar membrane protects plants against cell wall damage
Full text linkVacuoles are essential for cellular metabolism and growth and the maintenance of internal turgor pressure. They sequester lytic enzymes, ions and secondary metabolites that, if leaked into the cytosol, could lead to cell death. Despite their pivotal roles, quality control pathways that safeguard vacuolar integrity have remained elusive in plants. Here we describe a conserved vacuolar quality control pathway that is activated upon cell wall damage in a turgor-pressure-dependent manner. Cell wall perturbations induce a distinct modification-ATG8ylation-on the vacuolar membrane (tonoplast) that is regulated by the V-ATPase and ATG8 conjugation machinery. Genetic disruption of tonoplast ATG8ylation impairs vacuolar integrity, leading to cell death. Together, our findings reveal a homeostatic pathway that preserves vacuolar integrity upon cell wall damage
Data of the Insect Biome Atlas: a metabarcoding survey of the terrestrial arthropods of Sweden and Madagascar
Full text linkWe present the data from the Insect Biome Atlas project (IBA), characterizing the terrestrial arthropod faunas of Sweden and Madagascar. Over 12 months, Malaise trap samples were collected weekly (biweekly or monthly in the winter, when feasible) at 203 locations within 100 sites in Sweden and weekly at 50 locations within 33 sites in Madagascar; this was complemented by soil and litter samples from each site. The field samples comprise 4,749 Malaise trap, 192 soil and 192 litter samples from Sweden and 2,566 Malaise trap and 190 litter samples from Madagascar. Samples were processed using mild lysis or homogenization, followed by DNA metabarcoding of CO1 (418 bp). The data comprise 698,378 non-chimeric sequence variants from Sweden and 687,866 from Madagascar, representing 33,989 (33,046 Arthropoda) and 77,599 (77,380 Arthropoda) operational taxonomic units, respectively. These are the most comprehensive data presented on these faunas so far, allowing unique analyses of the size, composition, spatial turnover and seasonal dynamics of the sampled communities. They also provide an invaluable baseline against which to gauge future changes
Characterization of imogolite-type nanoparticles in Podzols: morphology and association with iron
Full text linkImogolite-type nanoparticles (ITN) are among the most extensively studied particles present in the Bs horizons of Podzols, as they are strongly associated with the adsorption processes of different anions in soils, including phosphate. The aim of this study was to assess the properties of ITN in soil, in order to increase the current knowledge of ITN regarding adsorption models. ITN were isolated from the B horizons of three Swedish Podzols and characterised in terms of size distribution, morphology, elemental composition, and association with iron. Appreciable amounts of ITN were found in two of the three soil samples studied, reaching up to 14 % ITN by mass if all oxalate-extractable Si is assigned to ITN. Furthermore, substantial amounts of Fe were also present in the selected soil samples. Proto-imogolite (PIM) was the predominant form of ITN, suggesting that tubular imogolite have a lower contribution for ion adsorption reactions in Podzols. Three types of PIM morphology were identified: structureless amorphous clusters, fragmented nanotubes, and globular aggregates. The studied PIM, which exhibited a particle size around 50 nm, contained up to 19 % Fe, while no detectable amounts of Fe were found in tubular imogolite. Regarding PIM, Fe atoms were evenly distributed in the structure, providing evidence for the presence of a substituted and/or surface-adsorbed Fe phase, rather than large ferrihydrite clusters. The present study provides novel insights into the properties of ITN and its association with Fe, which will aid in the development of models predicting the fate of oxyanions in Podzols and other ITN-containing soils
Lokal åtgärdssamordning av vattenvårdsåtgärder
Full text linkDen här rapporten bygger på en enkät- och intervjustudie riktad till personer som arbetar med åtgärdssamordning av vattenvårdsåtgärder lokalt i Sverige. Syftet har varit att belysa åtgärdssamordnarnas erfarenheter, utmaningar och behov, samt att identifiera förbättringsförslag för framtida organisering, finansiering och stödstrukturer.Enkäten besvarades av 48 personer med olika organisatorisk tillhörighet, varav hälften var kommunalt anställda. Resultaten visade att rollen som åtgärdssamordnare ofta är bred och komplex, samtidigt som oftast endast en person inom organisationen arbetar med denna typ av uppdrag. Behovet av kollegialt lärande och nationell samordning lyftes som centralt. Ett genomgående hinder i arbetet var bristen på långsiktig finansiering, både för anställningar och för genomförandet av större åtgärder. Även kravet på medfinansiering beskrevs som ett oproportionerligt administrativt hinder. Samtidigt beskrev respondenterna att långa handläggningstider för anmälan om vattenverksamhet och variationer mellan län i bemötande från Länsstyrelsen påverkar effektiviteten i åtgärdsarbetet.Intervjuerna med sex personer med gedigen kunskap och erfarenhet av åtgärdssamordning och vattenvård bekräftade och fördjupade enkätens resultat. De understrykte behovet av samordning och stabila strukturer som möjliggör kontinuitet och kompetensöverföring, och visade på att arbetet fungerar bäst där det finns ett team av personer med kompletterande kunskaper. Tydliga mallar, utbildningar och en samlad plattform för resurser och erfarenhetsutbyte efterfrågades. Flera lyfte behovet av en samverkansplattform som kan fungera som stödstruktur och kunskapsnod.Resultaten pekar på att det finns ett starkt engagemang och praktiskt kunnande bland Sveriges åtgärdssamordnare, men att det nu krävs strukturella förbättringar för att denna kraft ska tas tillvara på fullt ut
Invited review: Future directions for cow-calf contact research and sustainable on-farm applications
Full text linkProlonged cow-calf contact (CCC) is of growing importance to the dairy sector due to increasing societal interest, implementation of CCC on farms, and research efforts. Incorporating CCC into dairy systems may be a polarizing change for academics and farmers. However, by considering the challenges with curiosity, including those mutual to CCC and non-CCC systems, there may be an opportunity to collectively improve the management of dairy animals. The aim of this review was to describe current issues and constraints in CCC, propose opportunities to advance knowledge of CCC, and inspire forward-thinking questions for dairy systems. There are known challenges for CCC implementation, such as research reproducibility (e.g., suitable controls, validity types) and on-farm application (e.g., farmer perspectives, policies, and corporate standards). To facilitate practical solutions for farmers wanting to adopt CCC we need research describing the effects of CCC systems on animal health and behavior. Already researchers have begun to explore cow and calf performance and health, methods for decreasing stress at weaning and separation (e.g., duration of contact, gradual weaning), foster cows, and opportunities for positive animal welfare in CCC systems (e.g., affiliative and play behavior). However, because dairying takes place in a complex system, changes may affect different facets of the system's sustainability. We suggest that the development of CCC systems should happen in dialog with stakeholders. Cow-calf contact is an uncommon practice in dairy systems and exists in different contexts; thus, there are many questions to address before advice can be given to interested dairy stakeholders. Perhaps, these CCC-related questions are an invitation to contemplate how we want dairy systems to look like in 30 years
Does peatland rewetting mitigate flooding from extreme rainfall events?
Full text linkPristine peatlands are believed to play an important role in regulating hydrological extremes because they can act as reservoirs for rainwater and release it gradually during dry periods. Rewetting of drained peatlands has therefore been considered an important strategy to reduce the catastrophic effects of flooding. With the anticipation of more frequent extreme rainfall events in the future due to a changing global climate, the importance of peatland rewetting in flood mitigation becomes even more important. To date, however, empirical data showing that rewetting of drained peatlands actually restores their hydrological function similar to pristine peatlands are largely lacking, particularly for boreal fens. To assess whether peatland rewetting can mitigate flooding from extreme rainfall events and ensure water security in a future climate, we measured event-based runoff responses before and after rewetting using a BACI approach (before-after and control-impact) within a replicated, catchment-scale study at the Trollberget Experimental Area in northern Sweden. High-resolution hydrological field observations, including groundwater level (GWL), discharge, and rainfall data, were collected over 4 years, allowing us to detect and analyze 17 rainfall-runoff events before and 30 events after rewetting. We found that the rewetted sites experienced an increase in the GWL following rewetting and that this was consistently observed across all distances from the blocked ditch within the peatland. Our rainfall-runoff analysis revealed that rewetting significantly decreased peak flow and the runoff coefficient and reduced the overall flashiness of hydrographs, making the rewetted sites function more like the pristine control peatland. However, "lag time", which was already similar to pristine conditions, was pushed farther away from pristine conditions following rewetting. Yet, our results showed that the effectiveness of ditch blocking in flood moderation was strongly influenced by the initial condition and the catchment percentage of restoration, as one of our two rewetted peatlands did not show significant change, attributed to it being already similar to the pristine site, suggesting less treatment effect, and the other catchment, with higher restoration percentage, had a better response to treatment. In summary, our findings suggest that peatland rewetting has the potential to mitigate flood responses; however, further research over a longer time period is needed, as peat properties and the peatland vegetation will develop and change over time
Physiological response to weight carrying and associations with conformation traits in Icelandic horses used for tour riding
Full text linkBackground Weight carrying capacity is an important trait in riding horses and it may be associated with conformation. This study examined the physiological response to a ridden incremental weight carrying test in 16 adult Icelandic horses used for tour riding. Horses carried 20% (BWR20%), 25% (BWR25%), 30% (BWR30%) and 35% (BWR35%) of their body weight (BW) in tolt (similar to 5.7 m/seconds, 640 m/step), and associations with body measurements and back conformation (score) were examined. Horses were divided into two groups (narrow or broad back) and body measurements were collected. Plasma lactate was analysed in blood samples collected after each step in the exercise test, an exponential equation was fitted, and BW-ratio was calculated for 2, 3 and 4 mmol/L (BWRLa2, BWRLa3 and BWRLa4). Plasma creatine kinase (CK) and aspartate amino transferase (AST) were analysed at rest and 24 h post exercise.Results Four out of 15 horses did not reach a plasma lactate concentration of 4 mmol/L, even at BWR35%. A positive correlation was found between chest width and BWRLa4 and between the difference between height at withers and croup and BWRLa2 (P < 0.05). Hock circumference and the difference between height at croup and back were negatively correlated with BWRLa2 (P < 0.05). The change in CK from rest to 24 h post exercise was negatively correlated with the difference between height at withers and height at back and croup (P < 0.05).Conclusions The physiological response to weight carrying was relatively low. A wider chest, "uphill" conformation, straight backline and smaller hock circumference were associated with weight carrying capacity, but group (narrow or broad back) was not
A Comprehensive and Ultrasensitive Isotope Calibration Method for Soil Amino Compounds Using Orbitrap Mass Spectrometry
Full text linkBound amino compounds (amino acid and amino sugar polymers) comprise a significant proportion (similar to 40%) of soil organic nitrogen and therefore represent an essential source of nitrogen for plant and microbial nutrition. The analysis of their content and isotope enrichment still represents a significant challenge due to the low isotope enrichment levels reached under near-native soil conditions and the lack of isotopically labeled standards for some key amino compounds. In this study, we used both a C-13-labeled and an unlabeled amino acid mixture to establish isotope calibration curves for 16 amino compounds, using the 6-aminoquinolyl-N-hydroxysccinimidyl carbamate (AQC) derivatization method and ultrahigh-performance liquid chromatography with high-resolution Orbitrap mass spectrometry (UPLC-Orbitrap MS). Molecular ions of AQC-derivatives for all standard amino compounds were identified at the expected m/z values of the respective isotopologues. The isotope calibration curves exhibited excellent linear fits across the whole C-13 enrichment range and polynomial fits in the low C-13 enrichment range (R-2 > 0.990). However, the polynomial fitting terms differed between individual amino acids. Subsequently, we developed equations to relate the calibrated regression terms to the physicochemical properties of the respective amino acids, here mainly the ratio of amino compound-C atoms to total C atoms in AQC-amino compound derivatives. Based on these regressions, we could ultimately predict isotope calibration curves for those amino compounds unavailable as C-13 labeled standards, for example, muramic acid, hydroxyproline, and diaminopimelic acid. To test the model accuracy, we compared the outcomes of measured calibrations with predicted calibrations for amino acids where we had isotopically enriched standards. The results of linear regression between measured and predicted data were excellent, where R-2 was >0.97, and mean absolute (percentage) deviations, MAD and MAPD, were 0.334 and 15.8%. Finally, we applied both standard and predicted calibration curves to low C-13 amended soil samples and unlabeled controls to test the applicability of our model. The limit of detection (LOD) as the minimum detectable atom % C-13 incorporation of amino compounds ranged from 0.0003 to 0.14 atom % among different amino compounds. This general predictive model can be used to comprehensively quantify isotope enrichments across the entire soil amino compound profile, including amino sugars and proteinogenic and nonproteinogenic amino acids, providing valuable insights for a better understanding of the overall fate of different amino compounds in soils and other complex environmental systems